1. Field of the Invention
This invention relates to a magnetic recording tape cassette, and more particularly to a tape pad for use in a magnetic recording tape cassette for pressing the tape against the magnetic head of a recorder.
2. Description of the Prior Art
Recently, there have come into wide use in addition to standard type magnetic recording tapes, various types of magnetic recording tapes such as low noise type tapes, chrome tapes, and metallic tapes. Further, there have been developed various types of tape recorders which can change the tape feeding speed from the standard speed to half speed and/or double speed in order to change the recording bias or the reproducing equalizer, to lengthen the recording-reproducing time, or to improve the reproducing characteristics for making the best use of the properties of each type of tape. As is well known, the micro cassette tape recorder is arranged so that the tape can be fed either at 2.4 cm/sec. or 1.2 cm/sec.
In the tape speed variable tape recorder, it is expected that the electromagnetic conversion characteristics of the reproducing output or the like will be improved when the tape feeding speed is increased or the recorder is set to the double speed mode. However, conventionally, the expected improvement of the electromagnetic conversion characteristics could not be obtained. This is because the state of contact between the magnetic tape and the magnetic head becomes bad when the tape feeding speed is increased.
It has been found that the electromagnetic conversion characteristics at high tape feeding speed can be improved by improving the characteristics of the tape pad for pressing the magnetic recording tape against the magnetic head e.g. the surface evenness of the tape pad.
Generally, the tape pad is formed of felt. When making the tape pad, raw fur which, may be wool or rabbit fur, is pressed into a plate like form in a fulling step and then dyed a desired color. Thereafter, the plate-like body is subjected to a shearing step to produce surface evenness and then sliced to a desired thickness. On one surface of the sliced felt piece is attached a double-sided adhesive tape and the sliced felt piece is cut into the size required for the tape pad. The cut felt piece thus obtained is attached to a plate spring using the double-sided adhesive tape.
If the magnetic recording tape is pressed against the magnetic head with a tape pad having poor surface evenness, the magnetic recording tape cannot be uniformly brought into contact with the surface, especially the head gap portion, of the magnetic head. Therefore, the spacing loss is apt to occur upon recording and reproduction, and there arises significant deterioration in a high frequency tone. Further the contact force of the magnetic recording tape against the magnetic head changes subtly near the head gap and the fluctuation in the reproduced output is increased. This tendency becomes more significant as the tape feeding speed is increased.
When the length of the fibers (fur) of the felt is too short, the fibers cannot get intimately entwined and are apt to be dislodged from the surface of the pad. The dislodged fibers adhere to the tape and/or the magnetic head to cause "drop-out". When the length of the fibers is excessively long, the fibers cannot get uniformly entwined and ends of fibers are apt to project from the surface of the pad. The projecting end portion of a fiber, when once sandwiched between the tape and head, is apt to stay in that position since the other end thereof is secured to the pad. This causes "reproduction level drop", that is, lowering in the output level for a time longer than drop-out. This tendency is significant when the tape feeding speed is low.